A Rasch analysis was applied to identify those items which represent a global unidimensional latent HRQoL trait.
The results of the Rasch analysis provided a unidimensional global HRQoL index consisting of 10 items which sufficiently represents the longer KIDSCREEN profiles.
The psychometric properties of this index are such that the distribution of raw-scores resembles the theoretical expected normal distribution. Thus the index provides a good discriminatory power along the HRQoL-trait-continuum, shows only few ceiling/floor effects, and even raw-scores may provide interval-scaled HRQoL measurement. In addition the good internal consistency reliability (Cronbach’s Alpha = .82) and the good test-retest reliability / stability (r = .73; ICC=.72) enables a precise and stable HRQoL measurement. Additional statistical analyses show that the KIDSCREEN-10 Index is able to differentiate between different groups. Children and adolescents with a low score on the family affluence scale (FAS, effect size d=.47), with behavioural problems (SDQ, effect size d=.1.30) and with a high number of psychosomatic complaints (d=1.69) display significantly lower health related quality of life in comparison to the respective comparison group.
Answering the KIDSCREEN-10 Index requires only a few minutes.